(i) The reaction proceeds with an increase in volume. Therefore, an increase in pressure will shift the equilibrium in the backward direction. Therefore, the reaction mixture will now contain lesser amounts of CO and H2 and larger amounts of CH4 and H2O(g).
As a result, Kp value for the reaction will decrease.
(ii) The reaction is an endothermic reaction. So, an increase in temperature will shift the equilibrium in the forward direction. Therefore, the reaction mixture will now contain larger amounts of the products, (CO and H2), and lesser amounts of the reactants (CH4 and H2O(g)). The value of Kp will increase.
(iii) A catalyst has no effect on the position of the equilibrium. Therefore, the composition of the reaction mixture and the value of Kp will remain unchanged.